build: update android-configure script for npm

Now, that we can cross-compile node for Android, we also need to take
care of native node modules installed with npm. Since there is no way to
install and run npm on an Android device, we could instal node on host
and setup an environment for installing node modules and cross-compile
the native sources using Android NDK.
The changes to this script will allow npm, when installing a module, to
compile it using NDK.

In order to do this, the developer should do the following steps:
1. Compile and install node on host, using: configure, make and make
install
2. Build node for Android, using: source android-configure <path_to_ndk>
arch and make
3. Push node binary to Android device
4. Using the same session, configure npm arch using: npm config set
arch=<arch>
5. Install desired node modules using: npm install
6. Push installed node modules to Android device

Signed-off-by: Robert Chiras <robert.chiras@intel.com>
PR-URL: https://github.com/nodejs/node/pull/6349


Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>